Function pool_create

examples/stdlib.c:1744–1778

* Create a malloc() pool. Here, flags are mmap() flags. */

 * Create a malloc() pool.  Here, flags are mmap() flags.
 */
static struct malloc_pool_s *pool_create(int flags, void *base,
    size_t lb, size_t ub)
{
    if ((uintptr_t)base % MA_PAGE_SIZE != 0)
    {
        errno = EINVAL;
        return NULL;
    }
    ub += (ub == 0? MA_PAGE_SIZE: 0);
    ub += (ub % MA_PAGE_SIZE != 0? MA_PAGE_SIZE - ub % MA_PAGE_SIZE: 0);
    lb = (lb > ub? ub: lb);

    int fixed = (base != NULL? MAP_FIXED: 0x0);
    void *ptr = mmap(base, ub, PROT_NONE,
            MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE | fixed, -1, 0);
    if (ptr == MAP_FAILED)
        return NULL;

    flags |= MAP_ANONYMOUS;
    struct malloc_pool_s *pool = (struct malloc_pool_s *)base;
    ptr = mmap(base, lb, PROT_READ | PROT_WRITE, flags | MAP_FIXED, -1, 0);
    if (ptr != (void *)pool)
    {
        (void)munmap(ptr, ub);
        errno = ENOMEM;
        return NULL;
    }
    mutex_init(&pool->mutex);
    pool->base   = (uint8_t *)pool;
    pool->mmap   = (MA_PAGE_SIZE * MA_PAGES(lb)) / MA_UNIT;
    pool->end    = (MA_PAGE_SIZE * MA_PAGES(ub)) / MA_UNIT;
    pool->root   = MA_NIL;
    pool->flags  = flags;
    return pool;
}

/*
 * Destroy a malloc() pool.